sm8450-common: Change vbmeta_system rollback index location

"Rollback Index Location 1 is already in use."

Change-Id: If6ba66486acd9d949f64260cef36e0ebf88cac48

BoardConfigCommon.mk

@@ -90,6 +90,6 @@ BOARD_AVB_VBMETA_SYSTEM := system system_ext product
 BOARD_AVB_VBMETA_SYSTEM_KEY_PATH := external/avb/test/data/testkey_rsa2048.pem
 BOARD_AVB_VBMETA_SYSTEM_ALGORITHM := SHA256_RSA2048
 BOARD_AVB_VBMETA_SYSTEM_ROLLBACK_INDEX := $(PLATFORM_SECURITY_PATCH_TIMESTAMP)
-BOARD_AVB_VBMETA_SYSTEM_ROLLBACK_INDEX_LOCATION := 1
+BOARD_AVB_VBMETA_SYSTEM_ROLLBACK_INDEX_LOCATION := 2
 
 BOARD_MOVE_GSI_AVB_KEYS_TO_VENDOR_BOOT := true